论文题目:A multi-bit FIR filtering technique for two-point modulators with dedicated digital high-pass modulation path
作者:Xiaoyong Li, Woogeun Rhee, Wen Jia, Zhihua Wang
期刊:ISCAS 2015
年份:2015.24-27 May
卷(期)及页码:pp. 894 - 897
摘要:
This paper describes an effective way of relaxing the nonlinearity problem of the digitally-controlled oscillator (DCO) in the two-point modulator design. A separate coarse varactor array dedicated for the high-pass modulation significantly simplifies the nonlinearity calibration of the DCO with a few-bit control. In addition, a finite-impulse response (FIR) filter is designed for the multi-bit high-pass modulation path to reduce the quantization noise, while offering a time-interleaving operation to minimize the DCO sensitivity to the coupling during switching time. A two-point modulator based on a semidigital fractional-N phase-locked loop (PLL) is implemented in 0.18μm CMOS. Simulation results show that the proposed modulator can achieve 10Mb/s GFSK/GMSK modulations with the EVM of -37dB.